A cardiac arrhythmia is a condition in which the heart's normal rhythm is disrupted. Certain types of cardiac arrhythmias, including ventricular tachycardia and atrial fibrillation, may be treated by ablation (for example, radiofrequency (RF) ablation, cryoablation, ultrasound ablation, laser ablation, microwave ablation, and the like), either endocardially and/or epicardially.
The success of an ablation procedure depends largely on the quality of the lesion(s) created during the procedure. Further, in the case of pulmonary vein isolation (PVI) using a cryoablation balloon, success may depend on whether the cryoballoon has completely occluded the pulmonary vein (PV) being treated. In any ablation procedure, however, an important concern is preventing damage to non-target tissue, particularly non-cardiac tissue. For example, when performing PVI, non-target tissues such as the lungs, esophagus, vagus nerve, and phrenic nerve may be thermally affected by the treatment of the target tissue within the heart. This collateral damage may have permanent undesired effects on these non-target tissues.
There are several ways in which such non-target tissues may be monitored for the onset of thermal damage during an ablation procedure. For example, damage to the phrenic nerve may be detected by monitoring diaphragm function, and techniques such as fluoroscopy, electrocardiography and pacing, intracardiac echocardiography, and transesophageal or transthoracic ultrasound imaging may be used to directly visualize epicardial structures in an attempt to prevent collateral damage. However, these methods may involve the use of a great deal of additional complex and expensive equipment, and the procedures may be time-consuming and the results difficult to interpret.
Therefore, it is desired to provide a method and system for generating feedback during an ablation procedure in order to monitor lesion formation in target tissue and avoid unintentional damage to non-target tissue. It is further desired to provide a method and system for generating feedback that is easy to use, does not involve additional equipment, and can be used during an ablation procedure to allow for real-time monitoring.